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One for the mathematically minded...

Originally Posted by

**Goldsmith**
To make things simpler. The formula for working out the circumference of a sphere is Pi (3.142) x diameter, so each half sphere is half this total.

For a 15mm. diameter sphere. 15mm x 3.142 = 47.13mm (the whole sphere), divide by 2 = 23.56mm (half a sphere). So as a rough guide 2 discs 24mm. diameter will shape to a 15mm diameter sphere.

I hope this makes sense.

James

I understand what you are doing here but it does not take into account any stretching or thinning of the disc when using a doming punch, nor does it take into account the thickness of the metal.

Your formula works for a zero thickness material - but it is a good place to start to get an approximate size of the disk.

Stretching will require a smaller disk, whereas thickness will require a bigger one - how these two interact in real life depends on the type of metal, its thickness etc.

Sent from my iPad using Tapatalk

Last edited by BarryM; 30-11-2015 at 12:26 PM.

Barry the Flying Silversmith👍

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